C1240: ABS Hydraulic Pressure Differential Switch Input Short Circuit To Battery
What does C1240 mean?
C1240 is a diagnostic trouble code indicating "ABS Hydraulic Pressure Differential Switch Input Short Circuit To Battery". The ECU is detecting a voltage reading that is below the expected range in the anti-lock brakes circuit. This typically points to a wiring short, a faulty sensor, or a grounding issue.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- ABS warning light on
- Brake pedal feels different
- Unusual braking behaviour
- Intermittent warning lights
Estimated repair cost
Typical range in Australia (parts + labour)
Common causes
- Damaged or corroded wiring harness
- Loose or disconnected electrical connector
- Failed anti-lock brakes sensor or actuator
- Blown fuse in the related circuit
- Poor ground connection
What should you do?
This code sits in the braking system. Your normal hydraulic brakes generally still work, but the electronics layered on top of them, ABS, EBD and emergency brake assist, can drop out. You will not notice until you brake hard or brake on a wet or loose surface, and that is the moment they would have helped. Treat the car as needing a workshop rather than as safe to drive, and get it looked at before your next real trip.
Get a diagnosis for YOUR car
Code C1240 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.